<!DOCTYPE html>
<html lang="en">
<head>
  <meta charset="UTF-8">
  <meta name="viewport" content="width=device-width, initial-scale=1.0">
  <title>Document</title>
  <style>
    div {
      width: 100px;
      height: 100px;
      border: 20px solid red;
      padding: 20px;
      margin-top: 20px;
    }
    .div1 {
      background-color: #000000;
      box-sizing: border-box;
    }
    .div2 {
      background-color: yellow;
      box-sizing: content-box;
    }
  </style>
</head>
<body>
  <div class="div1"></div>
  <div class="div2"></div>
  <script>
    
  </script>
</body>
</html>